Factors affecting microwave-enhanced advanced oxidation process for sewage sludge treatment

Abstract

The microwave-enhanced advanced oxidation process (MW/H2O2-AOP) was applied to sewage sludge for nutrient solubilization and solids' disintegration. Four factors, temperature, hydrogen peroxide dosage, mixing, and solids concentration were chosen for a screening experiment, and were ranked according to their significance of influence on the process. In general, temperature and hydrogen peroxide dosage are the two significant factors affecting the process, while mixing is the least significant factor. Temperature was the most significant factor for the release of orthophosphate, and hydrogen peroxide dosage was most important in ammonia release. Solids disintegration, in terms of soluble chemical oxygen demand (SCOD), was largely dependent on temperature and hydrogen peroxide dosage. For volatile fatty acids (VFA) release, mixing was the most significant factor. At higher temperatures with mixing, more VFA was released into the headspace, resulting in less VFA retained in the solution. The best results of solids' disintegration and nutrient release were obtained at 120°C, and 0.80 g H2O2/g dry sludge.